Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quais provedores usam o servidor de troca?
 ###Tabelas: CREATE TABLE singles_titles_5 (singles_titles_5_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, Tournament VARCHAR, Surface VARCHAR, Opponent in the final VARCHAR, Score VARCHAR) CREATE TABLE variation_with_playing_cards (variation_with_playing_cards_id AUTO_INCREMENT PRIMARY KEY, 1st player's choice VARCHAR, 2nd player's choice VARCHAR, Probability 1st player wins VARCHAR, Probability 2nd player wins VARCHAR, Probability of a draw VARCHAR) CREATE TABLE defensive (defensive_id AUTO_INCREMENT PRIMARY KEY, Player VARCHAR, Sacks INT, INT'S INT, Yards INT, Average INT, Long VARCHAR) CREATE TABLE results_timeline (results_timeline_id AUTO_INCREMENT PRIMARY KEY, Tournament VARCHAR, Starts INT, Top-10s INT, Wins INT, Earnings ($) VARCHAR) CREATE TABLE snap-ins_and_hosts (snap-ins_and_hosts_id AUTO_INCREMENT PRIMARY KEY, Application VARCHAR, Version VARCHAR, Cmdlets VARCHAR, Provider VARCHAR, Management GUI VARCHAR)  
SELECT Provider FROM snap-ins_and_hosts WHERE Application = Exchange Server